Present day vehicular traffic in many areas can often be characterized as high density and high speed. Multilane highways afford the opportunity for passing on both sides of a vehicle, and aggressive drivers commonly weave their way through traffic, changing lanes many times in the process. Speed limits have been increased in many localities throughout the country. All this places demands on the driver to be aware of the surroundings and to be alert to changes which can happen quickly. It is also well known that side mounted mirrors have xe2x80x9cblind spotsxe2x80x9d where overtaking vehicles may go undetected.
With the above considerations in mind, a system which could provide information to the driver prior to a lane change, on vehicles in the xe2x80x9cblind spotxe2x80x9d of the mirror system, would provide an additional measure of safety. Furthermore, if this system could be incorporated into or added onto the existing structure of the side mounted mirror and provide visual indication to the driver when the side mirror is viewed, then the device would require no additional driver actions beyond what is normally performed in a lane change.
The method and apparatus of the present invention detects the presence of objects within a sensing volume that encompasses the xe2x80x9cblind spotxe2x80x9d of the side mirrors provided on all vehicles. The xe2x80x9cblind spotxe2x80x9d of the side mirror system is a property of the vehicle body design, the mirror position and the viewing position of the vehicle operator. The sensing volume is defined as the volume covered by one or more sensing beams, each of which detects the presence of obstacles along its line of sight within a given distance and spatial location. The number of beams, directional orientation and beam width are arranged to provide indication of any obstacle above a minimum size corresponding to a motor vehicle or motorcycle, that may be present in the sensing volume, which itself covers the vehicle""s xe2x80x9cblind spotxe2x80x9d to the rear and side of the vehicle.
Preferably, the invention is implemented in a system comprising a control unit and multiple transmitting and sensing units that working together (1) locate objects along the lines-of-sight of the respective sensing elements, (2) by time-of-flight or time interval analysis calculate the distance to the sensed object, and (3) provide indication of objects within a predefined sensing envelope or spatial location.
Advantageously, the system is implemented using pulsed infrared laser transmitters, photodiode receiver circuits including amplification and signal conditioning, a digital clock for elapsed time measurement, one or more digital signal processors or microprocessors for system control and algorithm realization, and a display module for indication of sensing volume status or presence of an obstacle.
The invention relies on the principle of the time-of-flight or elapsed time measurement of short infrared pulses to determine the distance, on a suitable algorithm to filter the result through a range gate corresponding to a selected range along the line of sight, and on multiple sensing beams to provide full target area coverage.
Additionally the system provides visual display at the location of the vehicle side mounted mirror permitting simultaneous viewing of the mirror image of the roadway and the indicator display of the present invention.
These and other objects, features and advantages of the invention will be more readily apparent from the following detailed description in conjunction with the accompanying drawings.